r语言 - 将列中的特定值转换为UNIX时间戳

Question

我有一个列在我的数据框架，这是一些日期和字符串值的混合。我想明确地选择日期并转换为UNIX时间戳，并保留字符串值。如何做到这一点呢?

示例数据

|column1|
---------
|2020-12-21 00:00:00|
|test1|
|test2|
|test3|
|2021-12-21 00:00:00|

预期的结果

|Column1|
---------------
|1608508800|
|test1|
|test2|
|test3|
|1608508800|

Answer 1

x = read.table(text = 'column1
2020-12-21 00:00:00
test1
test2
test3
2021-12-21 00:00:00', sep = ";", header = T)
uts = as.numeric(as.POSIXct(x$column1, format = "%Y-%m-%d %H:%M:%S", tz = "UTC"))
uts_i = which(!is.na(uts))
x$column1[uts_i] = uts[uts_i]
x
#      column1
# 1 1608508800
# 2      test1
# 3      test2
# 4      test3
# 5 1640044800

或与dplyr:

x %>%
mutate(
uts = as.numeric(as.POSIXct(x$column1, format = "%Y-%m-%d %H:%M:%S", tz = "UTC")),
column1 = coalesce(as.character(uts), column1)
) %>%
select(-uts)
#      column1
# 1 1608508800
# 2      test1
# 3      test2
# 4      test3
# 5 1640044800